The present invention relates to a method for production of a fluid separation module, specifically, a spiral type-fluid separation module, More particularly, it relates to a method for production of a fluid separation module having a hollow mandrel with one or more layer arrangements, each comprising a plurality of layer elements, wherein the method comprises horizontally fastening the mandrel to a means for rotating the mandrel around its axis so that the layer arrangements hang downward, and rotating the mandrel around its axis by means of the rotating means so as to wind the layer arrangements thereon.
In general, for production of a spiral type-liquid separation module, a plurality of layer elements consisting of a spacing layer for the passage of a permeated solution, a first semipermeable membrane sheet, another spacing layer for the passage of a feed solution and a second semipermeable membrane sheet, in sequence, are piled on top of one another to form one or more layer arrangements and then they are spirally wound about the mandrel on a table, However, with this production method, the differences in curvatures of neighboring inner and outer layer elements in the layer arrangements wound about the mandrel cause a difference in the winding velocities of the layer elements. This results in a non-uniform shifting and resulting wrinkles in the inner layer elements. The non-uniform shifting and resulting wrinkles would be readily avoidable if the neighboring layer elements were smoothly slidable on each other thereby enabling a slidable winding of the layer arrangements about the mandrel. However, the layer elements, such as membrane sheets and spacing layers employed in the liquid separation module, are not smoothly slidable because of friction therebetween. Moreover, this tendency becomes greater as the number of layer arrangements increases. This non-uniform shifting and resulting wrinkles unavoidably occur in the layer elements, particularly in the membrane sheets, and damage these membrane sheets, thereby adversely affecting the separation function of the liquid separation module. The wrinkles in the spacing layers for a permeated solution and a feed solution cause the local occurrence of pressure against the membrane sheets, resulting in damage and lack of membrane-sealing in the membrane sheets thereby adversely affecting the separation function of the liquid separation module.
For the purpose of elimination of this non-uniform shifting and resulting wrinkles, some improved methods have been proposed. One is described in U.S. Pat. No. 3,386,583 and U.S. Pat. No. 3,397,790 wherein the layer arrangements are wound about the mandrel while applying tension to the layer elements separately. Another is described in U.S. Pat. No. 4,137,113 wherein the layer elements, just before reaching the mandrel, are separated from each other and each is subjected to radial tension while being wound about the mandrel. However, these conventional methods require not only large scale-production equipment but also troublesome operation processes.